Machine tool



4 Sheets-Sheet 1 W. F; RIDGWAY MACHINE TOOL Filed May 15, 1937 Dec. 3, 1940.

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MACHINE TOOL Filed May l5, 1937 4 Sheets-Sheet 2 RUN FASTER A98 SLOWER INDICATE INDICATE Deq. 3, 1940. RIDGWAY 2,224,106

MACHINE TOOL Filed May 15, 1957 4 Sheets-Sheet 3 STOP JOG

FAST FEED TRAVERSE.

Dec. 3, 1940. w E RIDGWAY 2,224,106

MACHINE TOOL Filed May 15, 1957 4 Sheets-Sheet 4 FASTER RUN STOP OQQ PILOT .100

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HLAD FEED FATLR RUN STOP sun/m was: nsrmf FAST ER RUN STOP PAIL FEED LPUMP RESET Patented Dec. 3, 1940 UNITED STATES PATENT OFFICE The lngersoll 3 Machine Company, Rock ford, 111., a corporation of Illinois Application May 15, 1937, Serial No. 142,782 28 Claims. (01.90-21) The invention relates to improvements in machine tools, and is particularly adapted for large size machines such, for example, as cross-rail milling machines having a plurality of movable" eral, the present invention contemplates various improvements in the novel machine tool arrangement disclosed and claimed in my copending application Serial No. 9,134, filed March 10 4, 1935, and issued as Patent No. 2,089,814.

One of the objects of the present invention is to provide a machine tool having an improved control arrangement including a mobile panel that may be shifted bodily and manipulated by 16 the use of only one hand, a plurality of digitally operable switches being mounted on the panel within range of the operators thumb so that he can control even a large and complex machine with great convenience, nicety, and precision 20 from any desired point about the machine.

Another object of the invention resides in the provision in a machine tool having a plurality of operative machine tool elements, of a mobile control panel carrying a plurality of 25 switches adapted to eflect a multiplicity of con--,

trol operations on the various machine tool elements from any desired point about the machine, and a single indicating meter or the like on the panel operable at will to show the condi- 30 tion of operation of any selected one of the machine tool elements, thus indicating to the operator the exact condition of the various elements of the machine so that they may all be operated at maximum load and speed without 5 sacrifice in safety orprecislon of operation.

Another object of the invention is the provision in a machine tool having a machine tool element driven by a variable speed power actuating means, of a control meansadapted selectively to increase or decrease the speed of operation of the machine tool element, and a selectively operable indicating mechanism so interlocked with the control means that it is always rendered operative to apprise the operator of 45 the speed of the element upon actuation of the control means to effect a speed change.

Another object of the invention is the provision, in a machine tool having cooperating rotary and translatory machine tool elements, of 50 a novel interlock between said elements which prevents operation of at least one of said elements upon actuation of its normal control means except when the other of said elements is in operation, but which permits operation of 55 such one element at a relatively slow rate, ir-

respective of the operation of the other element, in response to the actuation of a separate log control.

Still another object of the invention is to provide a machine tool controlled from a mobile 5 control panel having a single visual indicating means thereon selectively operable to show a desired one of several operating characteristics of one or more elements of the machine tool such as their respective speeds or the loads thereon.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which Figure l is a perspective view of a cross-rail milling machine, embodying the present invention.

Fig. 2 is a wiring diagram of the spindle driving mechanism and control arrangement there- 5 for included in the machine tool shown in Fig. 1.

Fig. 3 is a wiring diagram of the table feed mechanism and control arrangement therefor included in the machine tool shown in Fig. 1.

Fig. 4 is an enlarged front elevation of the mobile control panel or pendant of the machine tool shown in Fig. 1 illustrating particularly the position of an operators hand with respect thereto while the control panel is in use.

Fig. 5 is a perspective view of the rear of the mobile control panel shown in Fig. 4 when supported by an operators hand, Fig. 5 being drawn on a somewhat smaller scale than Fig. 4.

The features of the present invention may be embodied in various types of machine tools for o performing different material removing operations and are particularly suitable for a single or multiple machine having one or more translatory elements and one or more power driven spindles or rotary elements. For purposes of illustration, the invention in itspreferred form is herein disclosed as embodied in what is commonly known as a cross-rail milling machine. It will be understood, however, that there is no intentionthereby to limit the invention to the. specific form or environment illustrated, but that the invention embraces all modifications, adaptations and alternative constructions coming within the spirit and scope of the appended claims.

General machine structure As shown in Fig. 1, the machine selected for purposes of illustration of the invention comprises an elongated horizontal bed II) which is provided at the top with parallel'spaced longitudinal ways. A work supporting table II is mounted for endwise reciprocatory movement on the ways and is adapted to be driven selectively in either direction at a rapid traverse rate or at a relatively slower feed rate. For convenience,

movement of the table II forwardly or to the left.

as viewed in Fig. 1 will be designated as the out movement and the reverse movement will be referred to as the in movement.

The driving means may be of any suitable type or form and is herein shown (see Figs. 1 and 3) as comprising a planetary gearing I2 having a central sun gear I3, a plurality of idler gears 4 journaled on a rotatable support l5 and meshing with the sun gear. and a ring gear l6 meshing with the idler gears. The support l5 constitutes the driven element of the gearing l2 and is operatively connected to a horizontal outlet shaft H. A worm I8 is secured to one end of the shaft I! and meshes with a worm wheel l9. Rigidly with the wheel I9 is a coaxial elongated spur gear 20 which meshes with teeth formed by peripheral notches intersecting the threads of a worm 2|. This worm meshes with an elongated gear rack 22 rigidly secured to the lower side of the table II and extending longitudinallythereof. Thus, a. translatory motion is imparted to the table H at a speed and in a direction depending upon the speed and direction of rotation of the shaft II. In the present instance, a feed motor 23 and rapid traverse motor 24 are operatively connected respectively with the external and internal gear member l6 and I3 of the differential gear mechanism |2. To obtain a feed movement of the table II, the sun gear I3 is held stationary and the table is driven only from the feed motor 23. When a rapid traverse motion of the table is desired, the feed drive is supplemented in a differential action by driving the sun gear |3 from the rapid traverse motor .24. Rotation of the sun gear l3 during the feed drive is prevented by a brake 25 (Fig. 3) which normally acts on the' armature shaft of the rapid traverse motor 24 and which is adapted to be released by an electric.

solenoid 26 when the rapid traverse drive is instituted.

Two vertical columns 21 and 28 are rigidly mounted at opposite sides of the bed It) and preferably substantially midway of the ends thereof and are connected at their upper ends by a horizontal bridge 30 spanning the table II.

Spaced parallel vertical ways 3|, 32, and 33 are formed on the forward and inner sides of each of the columns 21 and 28. An elongated horizontal cross-rail 34 is mounted for translation on the ways 3|, 32, and 33 and is adapted to be driven in either direction selectively at a rapid traverse rateor at a relatively slower feed rate. Two counterweights (not shown) are suspended respectively within the columns 2'! and 28 and are connected to the cross-rail 34 at points adjacent the columns by means of cables 35 running over sheaves 36 on the bridge member 30.

The driving mechanism for the cross-rail 34 preferably comprises two vertical rotary screws 31 and 38 which are positioned respectively between the front ways of the columns 21 and 28 and are anchored at their ends against longitudinal movement. These screws are interconnected by a shaft 40 and are adapted to be driven in synchronism either at a rapid traverse rate or at a relatively slower feedrate by suitablerapid traverse and feed motors (not shown) connected thereto through a suitable differential gearing mechanism. This driving arrangement is substantially identical in its general organization and arrangement with that described above for the table II.

The front of the cross-rail 34 is formed with vertically spaced parallel longitudinal ways 4| on which one or more tool heads may be mounted for horizontal translation. In the present instance, two selectively available tool heads 42 and 43 are illustrated. The head 42 includes a vertical spindle 44 which is mounted for rotation and axial drive and which is adapted to support a suitable tool such as an end face milling cutter 45 at its lower end. The head 43 includes a vertically reciprocable ram 46 adapted to support a rotatable cutting tool such as a milling cutter 41 adjacent its lower end which is driven by a suitable spindle-within the ram. The ram 46 is adapted for rotary adjustment as well as axial movement and means is provided to lock the ram in different angular positions. Self-contained motor drives (not shown in their entirety) are mounted respectively within the heads 42 and 43 for rotating the driving spindles of the cutting tools 45 and 41. 7

Power drive means is selectively available for traversing the tool heads 42 and 43 along the cross-rail 34 and translating the spindle 44 and ram 46 axially either at a. rapidtraverse or a variable feed rate. In its preferred form, this means comprises a rotary spline shaft 48 and a stationary screw 50 both of which extend through the tool heads 42 and 43 and are anchored at the ends of the cross-rail 34. Enclosed within the heads 42 and 43 are four connections (not shown) from the spline shaft 48 and under the control, respectively, of clutch actuators 5|, 52, 5|, and 52 The first two connections are adapted to cooperate with the screw 50, respectively, to

translate the heads 42 and 43. The other two connections include change speed mechanisms 52 and 52, and respectively provide the axial drives for the spindle 44 and ram 46. One end of the shaft 48 is adapted to be driven either at a rapid traverse or a variable feed rate through a planetary gearing similar to the gearing l2 and a. change speed mechanism controlled by an actuator 53 from feed and rapid traverse motors 54 and 55.

- General control arrangements An improved form of electrical control is provided for the various translatory and rotative drive mechanisms in order that all of the machine tool elements may be controlled with great nicety'and precision and operated with maximum efiectiveness. As is hereinafter described in greater detail, all of the control operations are preferably effected from a single mobile panel shown in the form of a pendant 56 that may be moved about and actuated by the use of one hand of the operator. More particularly, th various control switches on the pendant 56 are so arranged that the operator while maintainingthe position of the pendant with one hand is able at the same time to operate any of the switches selectively with a digit, preferably the thumb, of the same hand therebyaifording a maximum of convenience in operating the machine. To provide the pendant 56 of a size convenient for manipulation by one hand, the substantial number of switches thereon necessary to afford a full and eflicient control of the various driving mechanisms are arranged in very compact groups and should be required only to make and break low voltage circuits in order to obtain safety in operation. On the other hand, it is desirable to supply the various electric driving motors for the machine tool elements with current from a-relatively high voltage source it they are to operate most eificlently and occupy the minimum amount of space.

, normally closed overload relay contacts I3.

The control system illustrated which meets these requirements consists in general of individual sets of control circuits for the three translatory drives and the two rotative drives as well as two sources of electric current of di fierent pois available across main supply lines 58 and 80 while the low potential sourceis connected across supply lines 8I and 82.

The master switch 51 is under the control 01' a normally open secondary reset relay 83 having an actuating winding 84 controlled by a normally open push button reset switch 85. Upon closure of the switch 85, an energizing circuit is completed from supply line 8I through conductor-88, switch 85, and conductor 81 to one terminal of the actuating winding 54, the other terminal of the actuating winding being connected to the second low voltage supply line 82. Such energization of the winding 84 closes switch 83 completing an energizing circuit for actuating winding 88 of the master switch 51. Thus, one terminal of the winding 88 is connected to supply line 80 through conductors 10, II, and I2 and The other terminal of the winding 88 is connected to supply line 58 through conductor I5, normally closed emergency stop switch or secondary relay I8, conductor 11, reset relay 83, and conductors I8 and 80. Energization of the actuating winding 88 of the master switch 51 closes the nor+ mally open main contacts 8| thereof, interposed in supply line 82, as well as the normally open sealing contacts 82 and 83. At the same time, the normally closed auxiliary contacts 84 are opened thus breaking the circuit through conductor 85 between supply line 8| and 82 of a pilot lamp 88. The pilot lamp 88 is lighted only when the master switch 51 is open, thus indicating to the operator that the reset switch must be actu ated in order to set the machine in operation. The closure of contacts 82 and 83 completes a shunt sealing circuit about the reset switch 83 through conductor 81, contacts 83, conductor 88, contacts 82, and conductors 18 and 80 so that the main switch 51 will remain closed after a momentary actuation of the reset push button switch 85. It will be noted that the full high potential between supply lines 58 and 80 is applied to the actuating winding 88 of master switch 51 while the low potential between supply lines 8| and 82 is applied to actuating winding 84 of the reset switch or relay 83 so that the machine can only be set in operation when the control circuit voltage is on as well as the high potential. As a result, an eflective electrical interlock is had between the two sources of potential.

Control circuits for spindle drives The two sets 01' control circuits for the rotary spindle drives are alike and are connected in parallel across the various current supply lines and hence a description of the circuits for the spindle 44, illustrated in Fig.2, will sumce for both. A portion of the control circuit for the second spindle included inthe ram 48 is also shown in Fig. 2 so as to illustrate the interconnecting control arrangement for selectively rendering either or both of the spindle drives operative.

The spindle 44 is'aclapted to be rotated in either direction and at different selected speeds by an electric driving motor 80 enclosed within the tool head 42. The motor includes as its principal elements shunt and series field windings 88 and 84 and an armature 95 adapted to be connected reversely across th high potential supply lines either by primary switches 08 and 91 to effect right hand rotation or primary switches 08 and I00 to eilect left hand rotation of the spindle 44. The control -mechanism fo the spindle in the tool head 43 similarly inclu es a pair of'switches for effecting right hand rotation of the driving motor. one of these switches being designated by the numeral IOI and also includes a pair of switches for eflecting left hand rotation of the driving motor, one of these switches being designated by the numeral I02.

The spindle driving motors in the tool heads 42 and 43 are selectively cut in or out of circuit by secondary relays or selector switches I08 and I 04 respectively. These selector switches are in turn controlled by digitally operable two-position switches I and I08 respectively mounted on the pendant 58. In addition, the direction of rotation of the spindle 44 is controlled by a pair of selector switches or secondary relays I01 and I08 which are actuated by a two-position digitally operable switch IIO mounted on the pendant 58. A second two-position switch III (see Fig. 4) is also mounted on the pendant 58 and serves to control a similar pair of direction selector switches or relays (not shown) for the driving motor of the spindle and the tool head 43.

When the switch H0 is set for right hand rotation of the spindle 44 as shown in Fig. 2, movement of the on and o switch I05 to its on position completes energizing circuits for actuating windings H2 and H3 of the primary switches 88 and 91 so that the motor 80 is energized for rotation in a right hand direction.

Thus, upon closure of the switch I05 in its on switch H0 is positioned for right hand spindle rotation as indicated by the letters "R. H. in Fig. 2, an energizing circuit for actuating winding I20 of direction selector switch I0! is completed across the supply lines 8| and 82 through switch H0 and conductor I2I. The energization of winding I20 closes normally open contacts I22, I23, and I24 ofswitch I01.

After the selector switches I03 and I0'Ihave been closed as described above, the control circuit is conditioned for actuation of the driving motor contactors or switches 96 and 91 upon momentary closure of a run push button I26 on the pendant 56. It will be noted that either 6 or both of the spindle driving motors may be conditioned for operation by the selector switches I05 and I06 and also conditioned for a desired direction of rotation by the selector switches H0 and II I. Then, the selected number of spindle 10 driving motors are set in operation in the desired direction of rotation by a momentary actuation of the single push button I25. Such closure of the push button I25 completes an energizing circuit for an actuating winding I26 of a run switch or secondary relay I21 across supply lines 6| and 62 through push button switch I25 and conductor I28. The energization of winding I26 closes normally open contacts I30 and I3I of run switch I21 thereby completing an energizing circuit for the actuating windings of the spindle driving motor switches. Thus, with the selector-switch positioning described above, the switches 96 and 91-are closed. Common terminals of the actuating windings H2 and II3 of switches 96 and 91 are connected to one supply line 60 through a conductor I32. The other common terminals of the windings II 2 and H3 are connected to the second high voltage supply line 58 through a conductor I33, contacts I22, conductors I34 and I35, contacts II6, conductor I36, contacts I30, conductor I31, contacts 82, and conductors 18 and 80.

Upon energization of actuating windings II 2 and H3 of the driving motor contactors 96 and 35 91 as described above, the main contacts MI and I42 thereof are closed. At the same time, the normally open auxiliary contacts I43 and I44 of switch 96 are closed and normally closed auxiliary contacts I45 thereof are opened. Closure of the auxiliary contacts I43 completes a shunt sealing circuit about the contacts I30 of the run" switch I21 so that the main motor switches 96 and 91 will remain closed after a momentary actuation of the run" push button I 25. This shunt sealing circuit about the contacts I30 includes conductors 'I46 and I41, contacts I43, and conductor I48. Closure of the main switch contacts MI and I42 completes an energizing circuit for armature 95 of spindle driving motor 90 as well as for the series field 94 thereof. The shunt field 93 of the motor 90 is permanently connected across supply lines 58 and 60 through conductors I50 and I5I, variable resistance I52, and conductor I53. The closure of contacts I 4| connects one terminal of motor armature 95 to supply line through resistors I80 and I18, conductor i 54, contacts I4I, conductors I55 and I56. Closure of contacts I42 connects the other terminal of motor armature 95 to supply line 58 through con 60 ductors I51 and I58, contacts I42, series field 94, and conductors I60 and I50. It will also be noted that actuating winding I49 of relay I59 is energized upon such completion of the motor cir- -cuit thereby closing its normally open contacts I69 which shunt out a portion of the shunt field rheostat I52.

Similarly, the positioning of the manually operable selector switch H0 in the position marked L. H. in Fig. 2 sets up the control circuit for 70 energization of the primary switches 98 and I00 which efiect left hand rotation of the spindle driving motor upon a momentary actuation of the run switch I25. Thus, when the switch H0 is moved to its L. .H. position, actuating 78 winding I6I of selector relay I08 is connected across supply line 6I and 62 through conductor I62 and switch IIII. Such energization 1' winding I6I closes normally open ,contacts I63, I64, and I65 of selector relay I08. After the selector switch IIO has been moved to its position for 5 left hand rotation of the spindle driving motor and selector switch I05 moved to its on position the primary switches 98 and I00 are actuated in response to a momentary actuation of the run" push button I25. Thus, the common 10 terminals of actuating windings I66 and I61 of switches 98 and I00 respectively are permanently connected to supply line 60 through conductor I32, while the opposite common terminals thereof are connected to the other high voltage supply 15 line 58 through conductors I68, I10, contacts I63, conductors I34 and I35, contacts II6, conductor I36, contacts I30, conductor I31, contacts 82 and conductors 18 and 80. Energization of actuating windings I66 and I61 closes not only the nor- 20 mally open main contacts HI and I12 of switches 98 and I00 but also closes the normally open auxiliary contacts I13 and I14 of switch 98 and opens the normally closed contacts I15 thereof. Closure of the auxiliary contacts I13 completes 25 a shunt sealing circuit about contacts I30 of run relay I21 through conductors I46 and I48. Closure of main contacts I1I of switch 98 connects one terminal of motor armature to supply line 58 through conductors I56 and I55, con- 30 tacts I1I, conductor I16, series field 94 and conductors I60 and I50. The other terminal of the motor armature 95 is connected to supply line 60 through conductor I51,contacts I12, conductor I11, and resistance I18 and I80. It will thus be seen that the spindle driving motor 90 is connected for left 'hand rotation upon the. actuation of the 'contr'ol'devices as described above. In addition, the relay I59 is closed as before, shunting out a portion of the shunt field--4 resistor.

An arrangement is also provided for selectively varying the speed of rotation of the spindles of the tool heads 42 and 43. This speed control arrangement preferablyincludes operat- 4r ing switches which can be utilized to selectively; vary the speed of either of the spindles from the pendant 56 just as the single run push button I25 can be used to start either of the spindles from the pendant. In the machine illus- 50 trated, the speed of the spindle driving motor 90 is varied by changing the setting of the shunt field rheostat I52 through the medium of a reversible rheostat operating motor I8I. This motor I8I includes an armature I82 and a pair of 55 field windings I83 and I84 which may be alternatively connected into. circuit for operation of the motor in one direction or the other. The armature I82 is shunted across resistor I85 by conductors I86 and I81. One terminal of the 60 resistor I 85 is connected to the supply line 60 by a conductor I88 while the other terminal thereof is connected to the common terminals of field windings I83 and I84 through a conductor I90. The opposite terminals of the field 65 windings I83 and I84 are alternatively connected to supply line 58 by selector switches or secondary relays I9I and I 92. The selector relay I9I is provided with a pair of normally open contacts I93 and an actuating winding I94 while 70 the selector relay I92 is similarly provided with a pair of normally open contacts I95 and an actuating winding I96. Closure of a normally open push button switch I91 on the pendant 56 connects one terminal of actuating winding I94 75 will be noted that the windings 2n and m as to supply line 8| while closureoia normally open push button I38 on the pendant 58 connects one terminal of actuating winding 188 to supply line 6|. The opposite terminalsoi the actuating windings I00 and I88 are connected to supply line 82 through a common-conductor 200 and contacts of a meter scale selector switch or secondary relay 202. In general. the closure of switches l0l or H02 energizes the rheostat motor I82 for rotation in one direction or the other so that on actuating the push button 597. for example, the rheostat will be rotated in a direction to cut resistance into the shunt field 93 and thereby increase the speed of the spindle driving motor 00 while closure of the push but ton I98 will cause the rheostat motor to cut resistance out 01' the shunt field oi the spindle driving motor and decrease its speed.

An interlock arrangement is preferably provided which makes it necessary for the operator to render a speed indicating device operative before the speed of the spindle driving motor can be changed. This is a particularly advantageous safety precaution since the operator is thus of necessity apprised of the exact speed change which he brings about by changing the setting of the rheostat I52. In thecontrol circuit illustrated, the speed indicating mechanism includes a millivoltmeter 203 mounted at the upper end of the pendant 58 and having a scale 204 thereon calibrated in terms of spindle R. P. M. Current is supplied to the millivoltmeter 208 from a tachometer generator 205 directly connected to the spindle M. The sets of contacts i23--l24 and iii-485 on the direction selector switches i0! and H18 respectively serve to connectthe generator 205 to the millivoltmeter 208 in proper circuit relation depending upon the direction of rotation of the spindle and consequently of the generator armature. The tachometer generator 205 is provided with a field 200 permanently connected to supply line 58 through conductors 209 and 248 and to supply line 60 through conductor 208".

The scale selector relay 202 serves to set up the proper connections for giving a reading on the R. P. M. scale 204 while an indicator switch'or relay 208 is operable to render the visual indieating meter 203 operative or inoperative at will. In addition, an interlock switch or relay 2!)? prevents energization of the rheostat operating motor l8! except when the visual indicating meter 203 is conditioned for indicating the speed of rotation of the spindle d4. Thus, when the manual direction selector switch H0 is closed for right hand rotation of spindle 44 thereby closing direction selector relay I01, the circuit for the indicating mechanism is completed and the circuit for the rheostat operating motor is condi- 0 tioned for completion by switches i9l or I92 upon closure of indicator push button switch 208 and movement of the manually operable scale selector switch M0 to its R. P. M. scale reading position. That is, when the snap switch 2i0 is 65 moved to its R. P. M. position energizing windmg 2i I, the scale selector relay 202 is connected across supply conductors BI and 62 by a conductor 2l2 and switch 2l0. Such energization of winding 2 closes not only the normally open contacts 20! but also normally open contacts H3 and 2M and opens the normally closed contacts H5 and H8.

Closure of indicator push button 208 connects actuating windings 2H and 2l8 of relays 208 and 75 201 respectively across supply lines SI and 82. It

connected in parallel with one common terminal connected to supply line 8| through conductor 220 and switch 208 and with the other common terminal connected to supply line 62 through conductor 22! and normally closed interlock contacts 222 of a second indicating relay 223 that in general serves to connect the meter 203 for indicating the speed of the spindle in ram 40. Such energization of switch actuating winding-2H closes normally open contacts 224, 225, and 226 of relay 208 and opens normally closed contacts 221 and 228 thereof. at the same time, energization of relay actuating winding 2i8 closes normally open contacts 230 and 238 thereof. The actuation of relays 202, 206, and 20'! as described above completes an energizing circuit for the meter 203 to indicate the speed of rotation of spindle 64. Thus, as the spindle is rotating in a right hand direction, one terminal of the tachometer generator 205 is connected to one terminal of the meter 203 through conductor 232, contacts i2 2, conductors 233 and 234, contacts 2M, conductor 235, meter resistance 236, and conductor 28!. The other terminal of generator 205 is connected to the second meter terminal through conductor 238, contacts i23 conductor 240, contacts 224, conductor 2M, contacts M3, and conductors 252 and 23d.

It will be understood that when switch 510 is set for left hand rotation of spindle M, relay i0! is open while relay Hill is closed so that conductors 232 and 238 extending from the generator 205 are connected to conductors 260 and 234 respectively through contacts ids and E65 rather than being connected to 236 and 2% respectively as described above through contacts $23 and 92d, the result being that the connection of the generator 285 to the meter 2% is reversed upon reversal in the direction of rotation of the spindle M.

The actuation of interlock relay dd? upon closure of the push button 2% conditions the energizing circuit of rheostat operating motor Hill for completion upon closure of the faster or slower push buttons $91 and res. Thus, upon closure of push button 391, for example, one terminal of energizing winding N4 of speed change relay idi is connected to supply lines iii through switch i917 and conductor 2% while the other terminal oi winding tee is connected to supply line 62 through conductor 200 and contacts Hill of scale selector switch 202. Energization of winding i9d efiects a closure of normally open contacts 1593 thus completing an energizing circuit for rheostat motor 98! of such character as to cause it to move the rheostat 552 to cut resistance into the driving motor shunt field 83 and thereby increase the speed of the driving motor. One terminal of rheostat operating motor i0! is connected to supply line' 58 through conductor 245, contacts 231], conductor 246, contacts 593, and conductors 241 and 248. The other terminal of motor iBi is connected to supply line 00 through conductors I86, a portion of resistance I305 and conductor E88 as described above In case push button I98 is closed to decrease the speed of spindle driving motor 80, field winding n84 rather than field winding I83 of rheostat operating motor MI is connected in circuit. Thus, one terminal of field winding I84 is connected to supply line 58 through conductor 250, contacts 230, conductor 25i, contacts I05, and conductors 241 and 248.

It should be noted that no sealing contacts are All provided for the speed change relays I 9| and I92 nor for the indicator interlock relay 201 so that the push buttons I91 or I98 and the push button 208 must be manually held in their closed positions duringv all of the time that the rheostatoperating motor I9I is energized for changing the speed of spindle driving motor 90. Ifhis .necessity for manually holding the push buttons in their closed positions centers the operators closes normally open contacts 254 and 254 there-' of and opens normally closed contacts 255 thereof. This conditions the main contactors including contactors IM and I02 of the control for the second spindle driving motor for closure upon actuation of the run push button I25.

A motor driven rheostat speed change arrangement (not shown) is provided for the second spindle driving motor which is identical with that illustrated and described above for the first spindle driving motor 90. In order to effect a change in speed of the second spindle driving motor, it is necessary to condition the meter 203 to indicate the speed of rotation of the second spindle by moving switch 2I0 to its R. P. M. indicating position and by closing push button 256. Closure of push button 256 connects one terminal of actuating winding 251 of the meter indicator relay 223 to supply line 6| through switch 256 and conductor 258. The other terminal of the winding 223 is connected to supply line 62 through conductor 260 and contacts 221 of indicator switch 206. It will be noted that the actuating windings 2I1 and 2! of relays 206 and 201 and actuating winding 251 of relay 223 are interlocked through normally closed contacts 221 and 222 thereof so that either switches 206201 or switch 223 must be actuated alone rather than simultaneously so that the meter 203 will indicate only the speedof one spindle or the other.

A tachometer generator (not shown) for the second spindle is connected to conductors 26i and 262, conductor 26I being in turn connected to one terminal of indicating meter 203 through normally open contacts 263 of relay 223, conductors 264 and 2, contacts 2I3 of relay $202 and conductors 242 and 243, while conductor 262 is connected to the other terminal of meter 203 through conductor 234, contacts 2I4 of relay 202, conductor 235, resistance 236 and conductor 231. Suitable connections (not shown) between the direction selector switch I II and the second spindle are interposed between the meter 203 and tachometer generator for the second spindle so that the proper alternations in connections will be had upon a change in direction in rotation of the second spindle and its attached tachometer generator, these connections being in general the same as those described above with respect to spindle 44.

Either or both of the spindle motors which happen to be running may be stopped at will by moving the switches I05 and I06 to their oil positions. For example, when the switch I 05 is opened while the spindle 44 is rotating in a right hand direction, the winding 4 will be deenergized and the contacts 6 opened; The circuit for the windings H2 and H3 will thereby be incircuit to the spindle motor of head 43.

It will be seen that in general the secondary switches are connected across the, low voltage supply lines 6I-62 while the primary switches and driving motors are connected across the high voltage supply lines 58-60. Thus, upon reference to Fig. 2, the actuating windings and digitally operable control switches therefor, of the secondary relays 68, I40, I21, I03, I04, I01, I08, I9I, I92, 223, 206, 201, and 202 are all connected across the low voltage supply lines 6 I62. On the other hand, the actuating windings of the primary contactors or switches 96, 91, 98 and I00 as well as spindle driving motor 90 are connected across the high voltage supply lines =5860.

Control circuits for translatory drives The three sets of control circuits for the translatory drives also are alike and are connected in parallel across the various current supply lines 58-60 and 6I-62 so that a description of the circuits for the translatory driving mechanism of table II, illustrated in Fig. 3, will sufiice for all.

In general, the table II is adapted for either in or out movement at a rapid traverse rate or a relatively slower but selectively variable feed rate. As was noted above, the feed and rapid traverse motors 23 and 24 are connected to the table II through the differential gear mechanism I2 which is of such character that the table II will be moved at a rapid traverse rate when both motors are in operation and will move at a relatively slower feed rate when only the feed motor 23 is in operation. The control arrangement illustrated is adapted to energize selectively either both of the motors or the feed motor 23 alone and also to' energize these motors for operation in one direction or the other in order to change the direction of movement of the table.

An improved arrangement is provided for connecting the feed and rapid traverse motors 23 and 24 in circuit relation to obtain the desired operation while utilizing the minimum number of control switches and relays. In this preferred arrangement, the feed motor 23 is connected across the high potential supply lines 58 and 60 by a pair of reversing switches or contactors 210 and 21I. These reversing contactors are alternatively actuatable to energize the feed motor for operation in one direction or the other. A rapid traverse motor contactor or switch 213 serves to connect the rapid traverse motor 24 in parallel relation with the feed motor 23 so that the rapid traverse motor will be energized for operation in one direction or the other depending upon the actuation of the same reversing contactors 210 and 21I which control the feed motor 23. Actuation of the reversing contactors 210 and 2" is controlled by a pair of selector relays 214 and 215.

Operation of either the rapid traverse or feed motors is initiated by a master switch 216 which is in turn controlled by a relay 211. This relay is provided with a pair of normally open contacts 218 which are closed by an actuating windmain switch 216.

run" push button switch 281, the relay wind- 1 ing 288 isconnected across the' low voltage supply lines 6l--62 by switch 28! and conductor 282... Energization of relay winding 288 closes the relay contacts 218 which complete anenergizing circuit for actuating winding 283 of the Thus, one terminal of the winding 283 is permanently connected to supply line 68 through conductor 284 while the other terminal thereof is connected, to;an interlock feeder supply line 285 through conductor 286, normally closed contacts 281 of a jog-switch or relay. 288, conductor 298, normally closed contacts 29l of a stop switch,.or relay 292, conductor 293, contacts 218 of starting switch or relay; 211, and conductor 294. This energize.- tion of actuating winding 283 of the main switch 216 closes the normally open sealing contacts 295 thereof as well as its normally open main contacts 296 'and 291. The sealing contacts 295 complete a shunt sealing circuit about the starting relay contacts 218 through conductors 298 and 388 so that the main switch,218 will remain closed after a momentary actuation of the manually operable run push button 286.

Closure oi: the main contacts 298 and 291 of switch 21.8 completes an energizing circuit for one or the other of the reversing contactors 218 or 21l depending upon the setting of a manually operable snap-type selector switch 3M which controls the selector relays 214 and 215.

Thus, if theselector switch 88f? isset for in".

movement ofthe table it, this being its position shown in Fig. 3, one terminal of an actuatingwinding 882 of selector relay 215 will be connected to the low voltage supply line ti through switch 9M and conductor 889 whilethe other terminal of the actuating winding will be connected to low voltage supply line t2 through a conductor 88d, normally closed limit switch 885 and a conductor 888. Thisenergization of actuating winding 882 closes the normally open" contacts 38'17, 888, and 898. An energizing circult is thus completed for actuating winding 8i i of the reversing contactor Elli. One terminal of this winding is permanently connected to sunply line 88 through conductors tit and did while the other terminal of thewinding is connected to supply line 58 through conductor did, contacts 298,, conductors tit and did, contacts till of and 828, contacts 825 of relay did and conduc tors till and 808. In such case, the normally open contacts 828, 825, and 828, of relay 217d are closedupon energization of relay actuating winding till. This winding til is energized upon movement of the switch 3M to its out p051- tlon, one terminal or the winding being connected to the supply line 86 through switch 88!! and conductor 928 while the other terminal is connectedto supply line 82 through conductor 338p normally closed limit switch 88! and conductor 332: l

The energization of winding 3 of reversing contactor 218 closes ,the normally open contacts 333, 334, and 335 of this contactor. which serve r to connect the motor 23 across the high voltage supply lines 58 and 68., It will be noted that the feed motor 23 is provided with an armature 336, a. shunt field winding 331 and a series field winding 338. 'One'terminal of the shunt field winding 3311s permanently connectedto the sup--.

ply line 58 through conductors 348 and 3 while the other terminal is normally connected to sup,-

ply line 68 through conductor 342 and rheostat through conductors 348 and 358, contacts 335,

conductors 3!", 352; and 353, contacts354 of relay 359, and conductor M3. The actuating winding 359 of relay 359 is normally connected across supply lines 58 and 68 when feed motor" The other terminalof motor arma- 1 23 is running. Thus, one terminal is connected to supply line 68 through conductor 3H3 while the other terminal is connected to supply line 58 through conductor 369, normally closed contacts 4910f jog relay-288, conductor 458, contacts 333 of contactor 218 or contacts 856 of contactor 2H, and conductors 488 and 46l. The

feed motor 23 is thus energized for rotation in a direction to move the table M "in at a relatively slow feed rate.

Similarly, the motor 23 will be energized to move the table ll out" atfa relatively slow feed rate upon closure of the normally open contacts 955, 357i, and 858 of the reversing contactor fill. ries field winding 398 is permanently connected to supply line 58 as described above while the other terminal is connected to the armature 888 in the; opposltesense to that described above, that is, one termlnal'of the series field winding .888 is connected to one terminal of the armature dddthrough a conductor 9%, contacts i358,

' conductors the and 898. The other terminal oi the armature 898 is connected to supply line" 88 through" conductors. t ll and 388, contacts 89?,

conductorsiltd and .858, resistor 95d, and conductor M8. The shunt ,ileld winding iltl of course remains permanently connected across the supply lines as before.

A relay 889, provided with an actuating winding 889 is adapted to control the how of current to a signal lamp so that the latter will he lighted whenever feed motor '28 is operating. One terminal of winding 889 is connected to supply line 88 through conductor tit while the other is connected to supply line 58 through conductors 8% and 958, contacts 3:338 ot contactor till or contacts 858 of contactor fill, and conductors 88d and till. Energlzation of relay winding 889 upon closure of contactors 8178 or 2H closes relay contacts 89 completing a circuit for pilot lamp 8E9 across supply lines ti82 through a conductor 829, The use of a pilot lamp to indicate the operation of the feed motor is particularly advantageous because the feed rate is often so slow that no motion of the table is apparent from a casual inspection. Consequently, the operator might go away andleave the machine running and consequently liable to In such case, one terminal of the se-- cluded to call to his attention the fact that the teed motor was operating.

If it is desired to increase the speed of translation of the table II, the rapid traverse motor 24 is set in operation. Only the armature 36l of this motor has been shown in order to simplify the illustration but it will be understood that it may be provided with both series and shunt fields, which are connected in substantially the same manner as those described above for the feed motor 23. Operation of the rapid traverse motor 24 1 s initiated by a digitally operable push button switch 362' which connects actuating winding 363 of a relay 363 across the low voltage supply line 6i--62. Energization of the actuating winding 363 closes the normally open relay contacts 364 completing an energizing circuit for actuating winding 365 of the rapid traverse motor contactor 213. Thus, one terminal of the actuating winding 365 is connected to supply line 56 through conductor 366, contacts 364 and conductor 361. The other terminal of the actuat ing winding is connected to supply line 66 through conductor 368, manually operable switch 316 and' conductor 31!. This energization of actuating winding 365 closes the normally open contacts 312 and 313 of rapid traverse contactor 213, thus connecting the rapid traverse motor 24 in parallel relation with the feed motor 23.

The closure of contacts 312 completes a circuit between common terminals of the motor armatures 336 and 36! through conductors 341, 314,

.contacts 312, and conductor 315, the other common terminals of the motor armatures being permanently connected together by a conductor The closure of contacts 313 of the rapid traverse contactor 213 energizes the brake solenoid 26 so as to release the brake 25 and permit rotation of the rapid traverse motor armature.

Thus, one terminal of solenoid 26 is normally connected to supply line 56 through conductor 366 while closure of contacts 313 connects the other terminal to supply line 66 through co'nductor 311, contacts 313, conductors 316 and 366, switch 316, and conductor 3".

The speed of the feed motor 23 may be selec-' tively varied by a speed control mechanism which is, in general, similar to that described above for the spindle driving motor 66. It includes as its principal elements the variable setting rheostat 343 which is operated by a reversible electric motor 316. This rheostat operating motor includes an armature 386 and alternatively ,energizable field windings 36l and 362. Common terminals of the field winding are connected together by-a conductor 363 which is also connected to one terminal of the armature 366.. This armature is connected across a resistor 364 by conductors 385 and 386, one terminal of the resistor being connected to supply line 66 through a conductor 361. The opposite terminals of the field windings 36! and 382 are alternatively connected to supply line 68 by speed selector relays 386 and 366 respectively. A pair of digitally operable push button switches '3! and 362 mounted on the pendant 58 serve to complete the energizing circuits of actuating windings 363 and 364 of the relays 366 and'366 respectively across supply lines '6l--62. Upon energization of relay actuating winding 663 by closure of push button 36l, for example, the normally open relay contacts 365 are closed; thus connecting the motor field winding 364 to supply line 66 through conductors .366 and 361, contacts 365, and conductor 366. Similarly, energization oi relay actuating winding 364 upon closure of push button 362 closes normally open relay contacts 466, thus connecting. the relay field winding 362 to supply line 56 through conductors 366-361, contacts 466, and conductor 46!. When field winding 36l is energized, upon closure of push button 361, the rheostat operating motor 316 rotates in a direction to change the setting of the'rheostat 343 so as to increase the resistance in the circuit of shunt field 331 of the feed motor and speed up the latter. In the same way, when field winding 362 of the rheostat operating motor is energized upon closure of push button 362, the setting of rheostat 363 is changed to decrease the resistance in the shunt field circuit of the feed motor so as to decrease the speed of the latter.

It will be noted that no sealing circuits are provided for the relays 388 and 396 and as a consequence, it isinecessary to manually hold the-push buttons 36l or 362 in their closed positions while altering the speed of the feed motor 23, thus obviating the, possibility of an undue change in speed being had through forgetfulness on the part of the operator;

The feed motor 23 may be operated at a special fast feed" rate if desired by manually maintaining a digitally operable fast feed switch or push button 462 in its closed position. This type of operation is desirable where light cuts are being taken since the cutting tool can then 463 of a control relay 464 across supply lines 6| and 62, thus energizing the same. In general, the control relay 464 serves to shunt out the rheostat 343 and substitute for it a fixed resistance element 344, which has a relatively higher resistance, in the energizing circuit of the shunt field 331 for the feed motor 23, thus increasing the speed of operation of the latter. Upon energization of relay winding 463, the normally open contacts 465 of relay 464 are closed while the normally closed contacts 466 thereof are opened. Upon such closure of contacts 465, a shunt circuit is completed about the rheostat 343 through conductors 461 and 466, contacts 465, and conductor 416. At the same time, the opening 01' contacts 466 break the shunt circuit about the resistance 344 previously formed by:

conductors .4 and 6. It will be noted that as soon as the fast feed" switch 462 is released, relay 464 drops out thus reinserting the rheostat 343 in the motor field circuit. Moreover, the setting or the rheostat is unchanged so that by releasingthe button,462, the operation will continue at the speed for which the rheostat is set.

The table I I may be stopped at any time desired by opening the normally closed push button type stop switch "2. Such opening of the switch 412 interrupts the energizing circuit of actuating winding H3 01' stop relay 262 which is ordinarily connected across supply lines 6 |62. The deenergization of actuating winding 3 opens the normally closed contacts 26] of stop relay 262, which are interposed in the sealing circuit of the main switch 216 so that the latter.

is deenergizecl and moves toits open position. The opening of the main switch 216 of course deenergizes the reversing contactors 216 and 21! and disconnects both the feed and rapid traverse motors from the supply lines.

An interlock arrangement is preferably provided between the driving mechanisms'for the Closure of push button 462 connects a relay actuating winding spindle motor and table feed motor so that the control circuit for the translatory table or element will be rendered inoperative except when the driving mechanism for the spindles or rotary elements is in operation. This is a particularly advantageous safety precaution since the liabilityoi moving the work piece into contact with the cutting tool while the latter is at rest is obviated. In the control arrangement illustrated, this interlock arrangement includes the feeder line 285, which is connected to supply line 58 through the spindle motor selector switches and reversing contactors in such manner that no current will be supplied to the feeder 285 and consequently to the main switch 216 of the table control mechanism unless one or both 02 the spindle motors is in operation. Thus, upon reference to Fig. 2, it will be seen that when the first spindle, that is, spindle 44, is rotating, for example, in a right hand direction, a circuit is completed from feeder conductor 285 to supply line 58 through conductor 4, normally closed contacts 5 and H6 of reversing contactors IM and I02 respectively, conductor 4I1, normally closed contacts 255 of selector relay I04, conduc tors M8 and M9, contacts II1 of selector relay I03, conductor 420, contacts I44 of reversing contactor 93, conductors 42I and 421, contacts 82 of master switch 51, and conductors 18 and 80. Similarly, if selector switch IIII is set for rotation of the spindle 44in a left hand direction rather than a right hand direction, the circuit is the same as that described above except that it is completed through contacts I14 on reversing contactor 98 rather than contacts I44 of contactor 96. The reversing contactors WI and I02 are provided with similar auxiliary contacts for completing the circuit between feeler conductor 85 and supply line 58 when the second spindle in the tool head 43 is in operation and spindle 44 is idle. Thus, in case contactor MI is closed for rotation of the second spindle in a right hand direction, the circuit is completed from the feeder conductor 285 to supply line 58 through conductors 422 and 423, contacts 254 of selector switch I04, conductor 4I8, normally closed contacts I15 and I45 of contactors 88 and 96 respectively, conductor 424, normally closed contacts II8 of selectorswitch I03, conductors 420 and 425, contacts 426 of relays IOI, conductor 421, contacts 82 of master switch 51, and conductors 18 and 80. In case contactor I02 rather than contactor IN is closed for left hand rotation of the second spindle, the circuit is the same except that it is completed through contacts 428 of contactor I02 rather than contacts 426 of contactor I M. It should be noted that shifting switches H or III from their right hand to left hand positions or vice versa will also stop the spindle and interlocked feed motors. In each instance, the run" switch I25 must be closed for a moment after the change has been made to startthe spindle again. In general, each time the feed is stopped, it is necessary to press the run switch 28I as an incident to restarting.

The interlocking arrangement between the rotary and translatory driving mechanisms might without special provision cause some difliculty in case a second spindle motor is set in operation while the other spindle motor and table drive mechanism are both running. When it is desired to effect this operation, the run push button I25 (Fig. 2) is first closed. Then, if say the spindle 44 is running and the spindle of the tool head 3 is theme to be set in operation. the selector switch I06 is moved to its on" position. In such case, the second pair oi'contacts I" on the run relay I28 completes a shunt circuitthrough conductors 430 and I about the contacts on the selector switches I03 and I04 that form a part or the supply circuit tor the feeder conductor 285 and as a result, the latter supply circuit will not be interrupted during theswitching operation. I I

The interlock is preferably arranged in, such manner that if both spindlesare running, the table will be stopped upon a stoppage of one of the spindles. This is an advantageous safety precaution as the operator might accidentally stop one of the spindles without realizing it. Upon reference to Fig. 2, it will be seen that when both spindle motors are running, the interlock feeder 285 is connected to supply line 58 through contacts 254 of selector relay I04, con- 88 or contacts I44 of contactor 96, depending on which is closed, conductor 421, contacts 82 of mainswitch 61, and conductors 18 and 30. 'Then,

if either selector relay I03 or I04 is opened, stopping its associated spindle motor, the interlock feeder is deenergized thus deenergizing the table control as described above and stopping the table drive mechanism. However, upon occasion the operator may intentionally stop either one of the spindles without affecting the feeds. By depressing the run button I25 and operating the switch I or I06 to ofi position either spindle or both may be stopped without affecting any of the reeds which may be in use.

An additional digitally operable push button jog switch 432 is also available for effecting actuation of the reversing contactors 210 and 2'II but it is inefiective to maintain a sealing circuit. When the push button switch 432 is closed, a circuit is completed for an actuating winding 433 of the jog relay 288 across supply lines 3I-62. The energization of actuating winding 433 closes contacts 434, 435, and 435 and opens contacts 281 and 431. As was noted above, one terminal of each of the actuating windings 3H and 320 of contactors 210 and 21I is permanently connected to supply line 60 through conductors3l2 and 3I3. Upon closure of the jog switch 432, when the direction selector switch 30I is set for in movement, for example, the second terminal of the contactor actuating winding 3 is connected to supply line 58 through conductors 3I4 and 438, contacts 436, conductors 3I5 and 3I6, contacts 301 of selector relay 215, and conductors 3I1 and 318. Similarly, whenthe selector switch 30I is set for "out movement of the table, one terminal of actuating winding 320 of contactor 21I is permanently con-,

nected to supply line 60 while the other terminal is connected to supply line 58 through conductors 32I and MI, contacts 435, conductors 322 and 323, contacts 324 of selector relay 214, and conductors 3I1 and 3I8. It will be noted that the contacts of jog relay 288 in effect form a shunt circuit about the main switch 216 so that reversing contactors 210 and 2H will be actuated irrespective of Whether the spindle motors are running. In other words, the interlock described above including the feeder circuit 235 is preferably entirely omitted from the dog switch control circuit.

The control circuits governed by the "jog switch 432 are also preferably arranged so that shunt field circuit and by lnterposing a resistor.

442 in series relation with the feed motor armature 336. Upon closure of the jog switch 432, the "iog relay 288 is actuated as described above and the contacts 434 thereof are closed completing a shunt circuit about the field rh eostat 343. Thus, one terminal of the motor shunt field winding 331 is connected to supply line 58 through conductor 3 as'before while the other terminal thereof is connected to supply line 60 through conductors 342, 401, and 408, contacts 434 of "jog relay 288, conductor 0, contacts 406 of the "fast feed relay 404, and conductor 4| l. Consequently, both the rheostat 343 and resistor 344 are shunted out of-the motor field circuit. The actuation of the jog" relay 288 also opens contacts 431 thereby deenergizing actuating winding 350 of relay 359 and permitting the contacts 354 thereof to move to their open position. This opening of the relay contacts 354 breaks the normal snunt circuit about tse motor armature resistance 442 so that this resistance is connected in series with the motor armature. Thus, upon closure of the main reversing contactor 210, for example, one terminal of the feed motor armature 336 is connected to supply line 60 through conductors 348 and 350, contacts 335, conductors 35l, 352, and 3531, resistor 442, and conductor I3. Similarly, when the reversing contactor 2" is closed, the other terminal of feed motor armature 336 is connected to supply line 60 through conductors 341 and 346, contacts 351, conductors 352 and 353, resistor 442, and conductor 3l3. The decrease in the field resistance as well as increase in the resistance of the armature circuit of the feed motor serves to minimize the speeds of the feed motor so that the table H is moved at a relatively slow speed while the jog switch 432 is held closed;

From the foregoing, it will be seen that translatory movement of the table II may be initiated by closing the "run" switch 28! or "jog switch 432. The sealing circuit is closed, however,.only when the run switch 28| is actuated. The switches 432 and 402 as well as the rapid traverse switch 362 must all be manually maintained in their closed position as long as operation under their control is to be had. The sealing circuit closed upon actuation of run switch 21 may be interrupted at will to stop the normal feed by momentarily opening the stop switch 4 I 2 as was described above.

Means is provided for automatically interrupting the operation of the machine upon movement of the table II into either of its extreme end positions.- This means comprises the two limit switches 305 and 33l interposed respectively in the energizing circuits of the actuating windings 302 and 321 of selector relays 215 and 214. Both limit switches are normally closed and are mounted adjacent opposite ends of the bed l0 for actuation by the table I l. Movement of the table II into its extreme in. and out positions will open the switches 305 and 33l to deenergize the coils 302 or 321. The uninterrupted line will, however, permit initiation of table travel in the reverse direction. 1

It will be seen that in general the secondary switches in the translatory drive control circuit are connected across the low voltage supply lines til-62 while the primary switches and driving motors are connected across the high voltage supply lines 5860. Thus, upon reference to Fig. 3, the actuating windings and digitally operable control switches therefor of the secondary relays 388, 390, 211, 292, 280, 404, 214, 215, and 363 are all connected across the low voltage supply lines 6I-62. On the other hand, the actuating windings of the primary switches or contactors 210, 21!, and 213 as well as the feed and rapid traverse motors 23 and 24 are connected across the high voltage supply lines 50-60.

Visual indicating mechanism As was described above, a visual indicating mechanism such as the meter 203 is preferably mounted on the mobile control pendant 56 in order that the operator may obtain at will an indication of the speed of rotation of either of the spindles. An arrangement is also preferably provided for utilizing this same meter to indicate the feed rate of the table I l as well as of the rail 34 and of either the head 42 or the head 43 along the rail. In addition, an arrangement is preferably provided for utilizing the meter 203 to indicate the load imposed on either of the spindles during operation of .the machine. By s6 utilizing the single meter 203 to indicate a plurality of operating characteristics of various ele ments of the machine tool, the operator is afforded full information as to the operation of the.

machine and at the same time, the apparatus is sufiiciently compact that it may be mounted as part of a mobile control station that can be shifted about the machine. The operator is able to run the machine at maximum speed and load with safety when it is equipped with such an indicating mechanism on the control panel since he can move about the machine and carefully inspect the progress of the workwhile at the same time maintaining his hands directly on the control switches and having a visual indication' of the operating characteristics of the various machine elements directly before him.

The mechanism has been previously described by means of which an indication is had on scale 204 of the meter 203 of the speed of rotation of either of the rotatable cutting tool spindles. A scale 445 is also preferably provided on the I meter 203 which is calibrated in terms of inches per minute to visually indicate the feed rate. This may be the feed rate of either the table II, rail 34, or one of the tool heads 42 or 43. A manually operable selector switch 446 mounted on the control pendant 56 below the meter 2 03 connects the meter for indicating the speed of movement of .either the table, the rail, or the tool heads. As shown in Fig. 2, the switch 446 is a three position switch. In one position, it closes a contact 441 which serves to connect an actuating winding 448 of a relay 450 (Fig. 3) across supply line 6l-62. Energization of the winding 448 closes the normally open relay contacts 45l and 452 that complete a circuit from tachometer generator 453 (Fig. 3) to the meter 203. In addition, interlocking contacts areprovided on the meter selector relays 206 and 223 so that the tachometer generator 453, which is mechanically connected to the table feed mechanism, cannot be connected in circuit with the meter 203 when the latter is connected to the spindle tachometer generator 205.

The table drive mechanism tachometer generator 453 comprises an armature 454 and a field winding 455. One terminal of the field winding 455 is connected to supply line 60 through conductor 456. winding is connected to supply line 53 through conductors 451-458, either contacts 333 of contactor 210 or contacts 356 of contactor 21I, depending upon which' one is closed, and conduc- "tors 460-46I. The terminals of the tachometer generator armature 454 are connected to contacts 45I and 452 respectively of the indicating selector relay 450 through conductors 462-463, 464-465, contacts 325 and 326 of direction selector relays 214 or contacts 308 and 3I0 of direction selector relay 215, depending upon which one is closed, conductors 466-461, and conductors 468-410. The contact 45I of relay 450 is connected to. one terminal of the meter 203 through conductor 4H 1 (Figs. 2 and 3), conductors 235, meter resistance 236, and conductor 231. The other contact 452 of relay 450 is connected to the second terminal of the meter 203 through conductors 412-413, normally closed contacts 410 of indicator relay 223, conductor 415, normally closed contacts 228 01 indicator relay 206, and conductor 243. It will thus be seen that when switch 446 is moved to close contact 443, a circuit will be completed from the table drive mechanism tachometer generator 453 to the meter 203 so that a continual visual indication will be had of the speed of movement of the table.

In some instances, when the table II is being moved very slowly, for example, to move a work piece into some exact position, it may be desirable to have the meter 203 indicate the speed of movement in smaller increments: In order to accomplish this purpose, a multiplier has been provided for increasing the readings in multiples of I0. For this purpose, a relay 011 (Fig. 2) is provided having an actuating winding 018 and normally open contacts 480. Upon closure of a digitally operable push button switch 48E, the actuating winding 418 is connected across supply lines 6I-62 and contacts 480 are closed, thus forming a shunt circuit about the meter resistance 236 through conductors 082 and 483. As a result, the indicator needle of the meter 203 will move I0 divisions to indicate an increment of speed of one inch per minute rather than one division, for example.

Similar control circuits are provided for connecting tachometer generators included in the driving mechanisms for the rail 34 and for the shaft 48 which drives the tool heads" and 44. Thus, as shown in Fig. 2, when the selector switch 446 is moved to close contact 404, an actuating winding 485 of a relay 488 is energized, thus closing contacts 481 and 480 thereof, which connect a tachometer generator for the tool head drive mechanism in circuit relation with the meter 203. The details of this circuit and of the circuit for the rail feed tachometer generator have not,

been shown since they are identical with those for the table drive mechanism.

In order to connect the visual indicating meter 203 for indicating the load on the spindles of the tool heads 42 and 43, the meter scale selector switch 2I0 is moved to its open or "load" reading 4 position. In such case, the meter 208 is connected acrossxthe load resistance I (P18. 2) when indicatorswitc'h 208 is closed or across a similar load resistance in the field circuit of the driving motor for the second spindle when indicator switch 256 is closed. Thus, when it 'is The other terminal of the fieldindicated in Fig.4 with suitable legends on the the operation desired. In addition to the condesired to obtain an indication of the load on spindle 44 of tool head 42, indicator switch 208 is closed, thus closing contacts 225 and 226 which are interposed in the meter load reading circuit. Upon closure of these contacts, one terminal of 5 the meter 203 is connected to 'one terminal of load resistance I80 through conductor 231, normally closed contacts 2I6 of the scale selector relay 202, conductor 490, contacts 226 of relay 7 206, and conductor 092. The other terminal of 10 meter 203 is connected to the other terminal of the load resistance I80 through conductors 243 and 493, normally closed contacts 2I5 of meter scale selector relay 202, conductor 494, contacts 225 of indicator relay 206, and conductor 495. 15

Similarly, when indicator switch 256'is closed, one terminal of meter 203 is connected to a conductor 496 leading to one terminal of the load resistance interposed in the field circuit of the spindle driving motor in tool head 43 through conductor 20 231,-normally closed contacts 2I6 of relay 202, conductors 490 and 491, and contacts 498 of relay 223. The second terminal oimeter 203 is connected to a conductor 500 which is connected to the other terminal of the load resistance in the 25 second spindle driving motor circuit through con ductors 243 and 493, contacts 2I5 of relay 202, conductors 494 and 50I, and contacts 502 of relay 223. The load resistors are so related to the meter that the-percentage of load may be read on 30 the spindle R. P. M. scale 204. Thus, a reading of indicates a load of 100 per cent and so on.

Since the scale readings go to a value of more than 100, overload readings may also be had.

7 Mobile control station by groups of digitally operable push buttons or switches indicated generally by the numerals 503 and 500 (Fig. 4). Since all of the digitally operable controb'switches are interposed in low voltage circuits, the switches may be made very small to facilitate compact mounting without danger of breakdown due to arcing.

The digitally operable control switches for the 5 various elements of the machine tool are all preferably mounted on a single mobile control panel. These switches are arranged in groups as panel to indicate the relation of the groups 0! switches to the variouselements of the machine tool. The operator is thus able to determine at once the proper group of switches for effecting trols and indicating mechanism heretofore described as being mounted: .on the pendant 56, a digitally operable snap switch 505 is also preferably mounted thereon to control a driving motor of a coolant system. Finally, as a special safety precaution, an emergency stop switch is mounted at the bottom of the control panel or pendant 56 so that the operator can shut down the entire machine by the actuation ofa single switch in case of an emergency; This switch is indicated by the numeral 501 in Fig. 2 andg preferably II I groups"may be operated.

provided with a-prominent actuating bar 508 ex-' "thereby interrupting the energizing, circuit'of,

main switch 68, Upon the opening of main switch'58, the energizing circuits for the'contactors controlling the spindle. motors areinterrupted as are the energizing circuits for the contactors of the motors in the various translatory drives, thus bringing the entire machine to a stop. From the foregoing, it will be seen that the operator does not need to predetermine the proper feeds and speeds. He can feel his way with the various controlling adjustments for the .elements'of the machine tool until he obtains the maximum performance from the machine.

Due to the small size of the switches mounted on the control panel, it is comparatively thin so that it may be readily grasped at the side edge by the operator with one handas shown in Figs. 4 and 5. One or more straps are preferably provided on the pendant so that the thumb of the operator's hand willbe free to operate the switches. In the preferred construction illustrated, two rigid elongated straps 511 and 512 are disposed on opposite sides of the controlpendant or mobile panel 55 in spaced relation thereto. The operator is thus able to insert the fingers of say his left hand between the strap 511 and. the adjacent portion of the pendant 55 and in effect grasp the same by pressing the back of his hand against the strap 511 and pressing his fingers against the side and rear surfaces of the pendant. His thumb is thus left free to operate the various push buttons and other switches on the fiat front surface of the'panel. If-desired, the panel may of coursebe moved about by inserting the right hand between the strap 512 and the adjacent portion of the pendant in the same manner, or, in some cases, it may be desirable to use both hands simultaneously. The elongated openings between the straps 511 and 512' and the adjacent side edges of the pendant 56 make it possible for the operator to slide his hands up and down on the pendant so that switches in different The provision of such a mobile control panel that is adapted to be moved about by one hand of the operator adds not only to the efficiency and effectiveness of operation of 'the machine but also to its safety of operation. 'The operator in such case is not forced to remain in some more or less remote control station but can, in. fact,

stand on the table 11 while the machine is op-. erating or in any other position most convenient for-viewing theprogress of the work. Since he is thus able to inspect the work very closely, the machining operation can be performed with greater precision and rapidity. He is also in- 6 formed at once of any break'agedf a cutting tool or work piece, for example, so'that the machine can be stopped instantly before serious damage occurs. The provision of a single visual indicating mechanism which may be utilized to register 0 the operational characteristics of ny one of the elements of the machine tool in hatever posi-' tion the operator may be also contributes to the efficiency of operation of the machine.

A For the convenience of the operator, an ar- TI-rangement is provided for suspending the pendant or mobile controlpanel 55 above A portion of the machine so that it may be left in such position unsupported by the hands of the operatonwhile he makes any necessary adjustments of the work piece. He is also relieved of the necessity. of 5 supporting all or most of the weight of the pendant while the machine is operating. This suspension arrangement, is substantially identical with that described and claimed in my prior application Serial No." 9,134 referred toabove and consequently need not be described here in detail. In general, the pendant 55 is suspended -from the forward end of a rigid, generally horizontal conduit 513 by a flexible armored conduit 514-(Fig.1)'. Atflexible cable 515 is attached to 15 the conduit 513 so that the leads therein are directed through the latter and the conduit 514 to the pendant 55. The conduit 513 is mounted intermediate its ends for horizontal and vertical pivotal'movements on the free end of a rearward- 1y extending arm 515 supported at its forward end by a vertical pivotal connection 511 on the bridge member 30. A counterweight 518 is mounted on a rearward extension formed on the conduit 513.. Horizontal adjustment of, the pendant 55 will swing the conduit 513 laterally and also'cause a lateral movement of the am 515 so that the combined linkage minimizes the outward movement 'of the pendant away from the rail 34 upon latera] adjustment thereof.

Manual adjustment mechanism An arrangement is preferably provided to adapt the table 11 for manual adjustment or positioning. Such an arrangement is especially advantageous in setting the table and a work piece supported thereby in some particular desired position with respect one of the cutting tools. In

the construction ustrated, manual longitudinal 0 adjustment of the table 11 is effected by means 7 Y of a" hand wheel 524 (Figs. 1 and 3)-. which is mounted on a shaft 525. The inner end pf the shaft 525 is provided with a bevel gear 525 movable into and out of operative engagement complementary-with a bevel gear 521 connected tothe shaft of the rapid traverse motor 24. The shaft 525 is longitudinally slidable and is biased by a compression spring 520 to a'position in which the bevel gears are out of engagement. Upon pushing the hand wheel 524'inwardly, the bevel gears are moved into engagement so that the table is moved upon a subsequent rotation of the hand wheel. I,

Movement of the hand wheel to a position in 55 which it is operatively connected with the table operating mechanism also serves to release the w brake 25 from the shaft of the rapid traverse motor.. For this purpose, an operating arm 529 is attached to the switch 310. The operating arm 60 520 engages suitable collars 530 on the hand wheel shaft 525 so that when the shaft is moved inwardly'to bring the bevel gears into engagement, the. switch 3101s swung to its uppermost position as viewed in Fig. 3. This closure of the switch 310 in its uppermost position completes an energizing circuit "for the brake solenoid 25. Thus, one terminal of the solenoid 25 is connected to supply line 58 through conductor 355 while the uother terminal 01' the solenoid is connected to supply line 50.through a conductor 521, switch 310, and conductor 311. The energization of solenoid 25 resulting from such closure of the switch I'll releases the brake 25 so that the shaft of the rapid traverse motor 24 may be rotated iii by the hand wheel 524 without impediment from the brake.

When the switch 310 is in its upward position as above described, the circuit extending from line 60 to the rapid traverse contactor winding 365 is broken; The opening of this circuit prevents accidental operation of the rapid traverse motor 24 whenever the hand wheel 524 is engaged therewith.

Brief rsum of'operation In starting the machine, the reset switch 65 on the mobile panel 55 is closed momentarily. Thereupon, the master switch 68 is closed permanently to establish connections to the supply lines.

All of the various elements of the machine tool may be controlled .from the single mobile panel 56 and the direction of each drive is adapted for independent control. For example, the rotation of the spindle 44 is under the control oi. switch IIO on the panel 56. Similarly, the direction of travel of the table Il may be reversed by means of the switch 30I on the panel 56.

The rotative drive for the spindle 44, for example, may be set into operation by moving the selector switch I05 to its on position and then closing the run switch I25. This spindle may then be stopped by moving the selector switch I05 to its oif position. The speed of rotation of the spindle 44 may be increased or decreased, respectively, by holding the adjust switch 208 in its closed position and then holding the switch I91 or switch I90 closed until the meter 203 indicates the desired speed has been attained. The rotative drive for the spindle included in the tool head 43 is similarly controlled by the o and off selector switch I06, run" switch I25, direction selector switch III, and speed adjustment switches 256, I91, and I98.

Assuming that one of the spindles is in opera tion, translation of the table Il may be instituted by closing either the run" switch 28I, jog switch 432, or rapid traverse switch 362 and may be stopped by actuating the stop switch A maintaining circuit is established when the "run switch 28I is closed. The fast feed, jog, and rapid traverse are effected only while the respective switches 402, 432, and 362 are manually held closed. Movement of the table may be had upon closure of the jog switch, however, whether the spindle motors are running or not. The rate of feed may be adjusted by closing either the switch 39I or the switch 392 until the indicator 203 shows that the desired feed rate has been attained. The direction of travel of the table II is'controlled by the direction selector switch 30I. The controls 503 and 504 are similar ly available for the other translatory drives.

If the table II is moved beyond either of its end positions, the control circuits will be interrupted by limit switches 305 or 33 I, thus stopping the machine by conditioning the control circuits in such manner that the table may be operated in the reverse direction. The loads to which the spindles are subjected are shown by the visual indicator 203.

If either of the spindles is subjected to a predetermined maximum overload, the master switch posed in the series field circuits of the driving motor 90. When a predetermined maximum overload current flows through the winding 522, the normally closed contacts I3 thereof are opened, thus breaking the circuit for the actuating winding 68 of the main control switch 51. Similar overload relays (not shown) are provided in the field circuit oi the driving motor for the other spindle also. The machine may also be stopped by actuation of the emergency stop switch 501.

I claim as my invention:

1. A machine tool comprising, in combination, a movable machine tool element, a power actuating mechanism for said machine tool element, a control means for effecting a selected variation in the speed of operation of said machine tool element, a visual indicating meter having a pair of scales thereon calibrated respectively in terms oi. speed and load, means including an interlock between said control means and said indicating meter for rendering the latter operative to indicate the speed of said machine tool element as an incident to the actuation of said control means, and means operable at will for rendering said meter operative to indicate the load imposed on said machine tool element whereby the operator may be apprised of the change in load on the element resulting from a selected change in speed.

2. A machine tool comprising, in combination, a movable machine tool element, a power actuating mechanism for said machine tool element, control means for effecting a selected variation in the speed of operation of said machine tool element, a visual indicating mechanism operable at will to indicate the speed of operation of said element, and means including an interlock between said control means and said indicating mechanism for rendering the latter operative as an incident to the actuation of said control means. Y

3. A machine tool comprising, in combination, a movable machine tool element, a power actuating mechanism for said machine tool element, control means for efiecting a selected variation in the speed of operation of said machine tool element, a visual indicating mechanism, means ineluding a switch operable at will for rendering said indicating mechanism operative to indicate the speed of operation of said machine tool element, and means operable by said last named means for rendering said control means operative to change the speed of said machine tool element only when said indicating mechanism is operative to indicate the speed of said element.

4. A machine tool comprising, in combination,

a plurality of cooperating relatively movable maoperation of any selected one of said elements,

and means including an interlock between said control means and said indicating mechanism for rendering any one of said control means inoperative to effect a variation in the speed of its associated machine tool element except when said indicating mechanism is conditioned for indicating the speed of operation of such associated machine tool element.

5. A machine tool comprising, in combination, a plurality of movable machine tool elements, individual power actuating mechanisms for each of said machine tool elements, individual electrically operated control means for varying the speed of operation of each of said machine tool elements, means including a pair of manual speed control switches selectively operable to render oneof said control means operative to increase or decrease the speed of its associated power actuating mechanisms, means including a selector switch for connecting said manual speed control switches in circuit relation with a selected one of said control means, a single visual speed indicating mechanism, means operable at will for rendering said visual indicating mechanism operative to indicate the speed of a selected one of said machine tool elements, and interlocking means for preventing a change in speed of any of said machine tool elements under the control of said manual speed control switches except when said indicating mechanism is rendered operative to indicate the speed of such machine tool element.

6. A machine tool comprising, in combination, a rotatable machine tool element, a translatory machine tool element, individual power actuating mechanisms for said elements, selectively operable control means for initiating operation oi said power actuating mechanisms, interlock means for preventing the operation of at least one of said elements except when the other of said elements is in operation, and a jog control means including a manually operable control member for initiating operation of said one element irrespective of the operation of said other element in response to the manual maintenance of said control member in a predetermined position. '7. A machine tool comprising, in combination,

a rotatable cutting tool element, a translatory work supporting element, individual power actuating mechanisms for said rotatable and trans- 40 latory machine tool elements, control means operable in response to a momentary actuation of a manually operable control member for rendering said power actuating mechanism for said translatory machine tool element operative, in-

terlocking means for preventing the operation of.

said power actuating mechanism for said translatory machine tool element in response to an actuation of saidcontrol member. except when said rotatable machine tool element is in operation, and means including a second manually operable control member normally biased to a predetermined position for rendering said power actuating mechanism of said translatory machine tool element operative to move the same in response to movement of said second control member against its normal bias.

8. A machine tool comprising, in combination, a rotatable cutting tool element, a translatory work supporting element, a power actuating mechanism for said rotatable element, a second power actuating mechanism selectively operable to traverse said translatory element at a relatively slow feed rate and at a relatively faster rapid traverse rate, control means operable in response to momentary actuation of a selected one of a pair of manually operable control members for rendering said second power actuating mechanism operative to traverse said translatory ele-- ment at a feed rate or rapid traverse rate, in- 7 terlocking means for preventing the operation of said second power actuating mechanism in response to an actuation of either of said control members except when said rotatable machine tool element is in operation, and means 76 including a third manually operable control member normally biased to a predetermined position for rendering said second power actuated mechanism operative to traverse said translatory machine tool element at a rate which is a fraction of said feed rate in response to movement 5 of said third control member against its normal bias.

9. A machine tool comprising, in combination,

a plurality of rotatable cutting tool elements, a translatory work supporting element, individual 10 power actuating means for each of said machine tool elements, selectively operable means for rendering said power actuating means for said rotatable cutting tool elements operative and inoperative, a second control means for selectively ren- 15 dering said power actuating means for said translatory work supporting element operative and inoperative, and interlocking means for preventing the operation of said translatory work supporting element except when at least one of said rotatable cutting tool elements is in operation.

10. A machine tool comprising, in combination,

a plurality of rotatable cutting tool elements, a translatory work supporting element, individual power actuating means for each of said machine as tool elements, selectively operable means for rendering said power actuating means for said rotatable cutting tool elements operative and inoperative, a second control means for selectively rendering said power actuating means for said translatory work supporting element operative and inoperative, interlocking means for preventing the operation of said translatory work supporting element except when at least one of said rotatable cutting tool elements is in operation, and means for maintaining said actuating means for said translatory element operative during the subsequent initiation of operation of one of said rotatable elements while the other of said rotatable elements is in operation. 40

11. A machine tool comprising, in combination,

a plurality of rotatable cutting tool elements, a translatory work supporting element, individual power actuating means for each of said machine tool elements, selectively operable means for ren- 45 dering said power actuating means for said rotatable cutting tool elements operative and inoperative, a second control means for selectively rendering said power actuating means for said translatory work supporting element operative and in- 50 operative, interlocking means for preventing the operation of said translatory work supporting element except when at least one of said rotatable cutting tool elements is in operation. and means for rendering said translatory work supporting 55 element inoperative in response to the stoppage of one of said rotatable cutting tool elements, subsequent to the simultaneous operation of all of said machine tool elements.

12. In a machine tool, a movable machine tool 60 element, electrically controlled power actuating means for said machine tool element, a mobile control panel having an elongated substantially rectangular front surface, a rigid strap secured to said panel and extending in spaced relation to 65 one longitudinal edge thereof, said strap being spaced from said panel a sumcient distance to permit the insertion of an operator's hand therebetween, and a plurality oi digitally operable control switches disposed on said front surface of said panel, said switches being located within range of the thumb of a normal human hand having the fingers thereof inserted between said strap and said panel.

13. In a machine tool, a movable machine tool element, electricallycontrolled power actuating means for said machine tool element, a mobile control panel having a plurality oi! digitally operable switches thereon connected in controlling relation with said power actuating means, a strap secured to said panel and adapted to receive the palm of an operators hand inserted between said strap and the adjacent portion oi the panel, whereby the operator may press the baokoi his hand against the strap and press the fingers of such one hand against the back of the panel to move the same about the machine while the thumb of such hand is left free to actuate said switches.

'14. In a machine tool, a movable machine too element, electrically controlled power actuating means for said machine tool element, and a mobile control panel having a plurality of digitally operable switches thereon connected in controlling relation with said power actuating means, said panel having a recess adapted to receive the fingers of an operator's hand inserted therein to shift the panel about the machine while leaving the thumb of such hand tree to manipulate said digitally operable switches.

15. In a machine tool, a movable machine tool element, electrically controlled power actuating means for said machine tool element, a mobile control panel having a plurality of digitally operable switches thereon connected in controlling relation with said power actuating means, and means including a flexible cable for supporting said panel adjacent said machine tool element, said panel having a recess adapted to receive the fingers of an operator's hand inserted therein to shift the panel about the machine while leaving the thumb of such hand free to manipulate said digitally operable switches.

16. A machine tool comprising, in combination, a plurality of movable machine tool elements, individual power actuating mechanisms for each of said machine tool elements, individual electrically operated control means for varying the speed of operation of each of said machine tool elements, means including a pair of manual speed control switches selectively,operableto render one of said control means operative to increase or decrease the speedoi its associated power actuating' mechanism, and means including a selector switch for connecting said manual speed control switches in circuit relation with a selected one of said control means.

17. A machine tool comprising, in combination, a translatory machine tool element, means including an electric motor fortraversing said element at a relatively slow feed rate, means including a second electric motor cooperating with said first named motor for traversing said element at a relatively faster rapid traverse rate; electrical supply lines for said motors, means including a pair of selectively operable reversing switches for connecting said first named motor across said supply lines to energize the same for rotation in a selected direction and thereby effect a feed movement of said machine tool element in a selected direction, and means including a third switch for selectively connecting said second motor in parallel relation with said first named motor to effect a rapid traverse movement oi. said machine tool element in a direction dependent upon the setting of said reversing switches.

18. A machine tool comprising, in combination, a transiatory machine tool element, means including an electric motor for traversing said element at a relatively slow feed rate, means including a second electric motor cooperating with" said first named motor for traversing said element at a relatively faster rapid traverse rate, electrical supply lines for said motors, means including a pair of electrically operated primary reversing switches for connecting said first named motor across said supply lines to energize the same for rotation in a selected direction and thereby efiecting feed movement of said machine tool element in aselected direction, a manually operable two-position selector switch for conditioning a selected one of said pair or primary reversing switches for operation, means including a reversing manually operable push button switch for energizing a selected one of said primary switches in response to a momentary actuation of said push button switch, and means including a switch for selectively connecting said second motor in parallel circuit, relation with said first named motor to effect a rapid traverse movement of said machine tool element in a direction depending upon the setting oi! said reversing switches.

19. A machine tool comprising, in combination, a translatory machine tool element, means including an electric motor for traversing said element at a relatively slow feed rate, means in-' thereby effecting teed movement of said machine tool element in a selected direction, a, manually g selector switch 'iorcondi tioifiiig a selected' ionepi said pair of primary reversing switches "for ,:operation, means including operableiwo-pos i a reversingmanuallyloperabie push button switch for energizing 'a'selected one oi. said primary 1 switches in response,to 'afmomentary actuation of said push buttonj sWitcmmeans including-a third primary electrically operable switch for connecting said second motorin parallel relation J with said first named motor to effect a rapid traverse movement of said machine tool element in a direction dependentupon the setting of said reversing switches, and means including a second manually operable push button switch for energizing said third primary switch only when said second push button switch is maintained in a predetermined position. v

20. A machine toolcomprising, in combination, a movable machine tool element, a selectively energizable power actuating mechanism operatively connected to said machine tool element, means including a brake for preventing movement of said actuating mechanism when deenergized, manually operable means for shifting said machine tool element, and means responsive to the actuation of said operable means for releasing said brake.

21. A machine tool comprising, in combination, a movable machine tool element, a rapid traverse motor and a feed motor, means including a differential gear mechanism for connecting said motors in operative relation with said machine tool element, a brake for selectively preventing movement of said rapid traverse motor,.an operating solenoid for releasing said brake upon energization of said rapid traverse motor, manually operable means operatively connected to said rapid traverse motor for shifting said machine tool element, and means responsive to the actuation oi said manually operable means for energizing said solenoid to release said brake.

22. In a machine tool the combination of a plurality of relatively movable machine tool ele-' ments, individual variable-speed power actuating mechanisms for said elements each provided with a variable-setting speed-change device, a single speed-change control, and selectively operable means for rendering said single control operative to change the setting of any selected one of said speed-change devices.

23. In a machine tool, a movable machine tool element, power actuating means for said element, a mobile control panel having an opening for receiving a portion of an operator's hand by which the panel may be moved laterally in opposite directions while leaving a digit of said hand free, and a plurality of control devices on said panel governing the selective operation of said power actuating means and operable selectively by said free digit while said portion of the operator's hand is inserted in said opening.

24. In a machine tool, the combination of movable machine elements, power driven means for actuating said elements individually, a control panel, means disposed at one side of the panel face and adapted to embrace a portion of an operators hand so as to permit the panel to be held and moved in different directions without the use of the thumb of said hand whereby to leave'the thumb free and movable at all times. and a plurality of manually operable control devices longitudinally spaced along said panel front and individually accessible to and operable by the thumb of said hand, said devices being operable to control the selective operation of said actuating means.

25. In a machine tool, the combination of movable machine elements, power driven means for actuating said elements individually, an elongated control panel, means extending along said panel for receiving and embracing a portion of an operators hand for holding the panel while permitting-shifting of the hand along the panel and leaving the thumb of such hand free and movable in front 01 the panel, and a plurality of manually operable control devices longitudinally spaced along said panel front and individually accessible to and operable by the thumb of said hand in different positions of the latter along the panel, said devices being operable to control the selective operation of said actuating means.

26. In a machine tool, the combination of machine tool elements, power driven mechanism for actuating said elements individually and at selec tively variable speeds, electric control means for said mechanism including a mobile panel movable about the machine so as to be accessible to the operator in different positions, a plurality of switches on said panel selectively controlling said actuating means to govern the movements of the different elements, an electrically actuated meter carried by and movable with said panel adjacent said switches and operable to indicate the rate of a plurality of said movements, and means also carried by said panel so as to be movable therewith and operable to associate said meter with said elements individually whereby to adapt the meter for indicating the speed of the associated element.

2'7. In a machine tool, the combination of machine tool elements relatively movable to perform metal-removing operations on work pieces supported in the machine tool, power driven mechanism located remotely from a work piece being operated on and operable to actuate said elements selectively at variable speeds, a control'panel disposed remotely from said mechanism adjacent a work piece being operated on so as to be accessible and visible to an operator in difierent positions about the work piece, a plurality of manually operable switch control devices on the face of said panel operable selectively to govern the operation of said mechanism in actuating said elements individually, a single electric actuated meter for visually indicating the speed of a plurality of said movements, and selector means carried by said panel and operable to associate the meter with said elements one at a time and thereby adapt the same for indicating the speed of the associated elements during actuation of the latter by said mechanism.

28. In a machine tool, the combination of a plurality of movable machine tool elements, individual power actuators for driving said elements at variable speeds, manually operable means for controlling said actuators selectively to initiate and terminate the movements of the dif ferent elements, manually controllable speed adjusting means operable selectively to increase and decrease the speed adjustment of the different actuators, an electrically actuated meter for indicating the operating speeds of said elements, switching means selectively operable to associate said meter with difierent ones of said actuators for indicating the operating speed of an individual machine tool element, and interlocking means actuated automatically by said switching means and operating to place said speed adjusting means in active control of one of said actuators automatically as an incidentto association of the latter with said meter and to withdraw such actuator from control by the adjusting means when the meter is associated with another of said actuators.

- WILLIAM F. RIDGWAY. 

